Man Charged In Deadly Oakland County Hyperbaric Chamber Explosion Pleads No Contest

TROY, MI — A man charged in connection with a hyperbaric chamber explosion that killed a 5-year-old boy in Oakland County pleaded no contest Tuesday.

Jeffrey Mosteller pleaded no contest to involuntary manslaughter, which carries up to 15 years in prison. Prosecutors dismissed a second-degree murder charge in exchange for the plea.

He is scheduled to be sentenced on Aug. 31.

Mosteller served as the safety director at the Oxford Center in Troy, where officials said 5-year-old Thomas Cooper was inside a hyperbaric chamber that exploded while receiving treatment at the center in Troy in January 2025.

The boy's mom, who was standing next to the chamber, was also injured in the explosion, officials said.

Investigators believe a single spark caused the explosion.

Three others, Oxford Center CEO Tamela Peterson, operations manager Gary Marken and chamber operator Aleta Moffitt are still awaiting trial.

Peterson and Marken are charged with both involuntary manslaughter and second-degree murder. Moffitt is charged with involuntary manslaughter and entering a false medical record.

Prosecutors accused the four workers of ignoring several safety guidelines for operating hyperbaric chambers. They said more safety steps could have prevented the tragedy, such as using grounding straps to prevent sparks. They also said other safety protocols from the National Fire Protection Association (NFPA) and Sechrist (the manufacturer of the hyperbaric chamber) were ignored.

Moreover, prosecutors said the medical facility's officials ignored daily maintenance checks and annual safety inspections. They said there was also no medical doctor or safety supervisor on site when Cooper was undergoing treatment, which was being performed by a non-licensed technician.

A lawyer representing the family told NBC News the boy was being treated for sleep apnea and attention-deficit/hyperactivity disorder. Prosecutors said those conditions are not approved to be treated with hyperbaric oxygen therapy.